scholarly journals Effect of non-condensable gas on heat conduction in steam sterilization process

2019 ◽  
Vol 23 (4) ◽  
pp. 2489-2494
Author(s):  
Yao Shen ◽  
Xiaozhi Wang ◽  
Zhuoya Yao ◽  
Xiangang Li
Keyword(s):  
Adverse Effect ◽  
Heat Conduction ◽  
Steam Sterilization ◽  
Gas Concentration ◽  
Pressure Steam ◽  
Sterilization Process ◽  
Thermal Sterilization ◽  
Semi Empirical ◽  
Gas Effect ◽  
Insight Into

Non-condensable gas has an adverse effect on heat conduction in pressure steam sterilization. An experiment was carefully designed to study the effect, and a semi-empirical formulation is obtained to predict the maximal temperature difference between outside and inside of a package. This paper gives a systematical insight into the non-condensable gas effect, and there is a threshold of the non-condensable gas concentration, beyond which the thermal sterilization becomes invalid for complete killing microorganisms.

scholarly journals A dry sterilization process for sterilized products after pressure steam sterilization

2021 ◽  
pp. 90-90
Author(s):  
Zhuoya Yao ◽  
Qing Zhang ◽  
Yao Shen ◽  
Xiangang Li ◽  
Xiaozhi Wang ◽  
...  
Keyword(s):  
Vapor Pressure ◽  
Negative Pressure ◽  
Steam Sterilization ◽  
Pressure Steam ◽  
Sterilization Process ◽  
The Relationship

A dry sterilization process is designed as a post-processual technology of the pressure-steam sterilization. Three experiments are carried out to study the effects of negative pressure, pulsating air, and pulsating steam, respectively, on the process. Antoine's formula is used to predict the relationship between the vapor pressure and the temperature, which can be applied in practice.

scholarly journals Surface Reformation of Medical Devices with DLC Coating

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 376
Author(s):  
Mao Kaneko ◽  
Masanori Hiratsuka ◽  
Ali Alanazi ◽  
Hideki Nakamori ◽  
Kazushige Namiki ◽  
...  
Keyword(s):  
High Pressure ◽  
Medical Devices ◽  
Diamond Like Carbon ◽  
Steam Sterilization ◽  
Dlc Coatings ◽  
Chrome Plating ◽  
Living Body ◽  
Dlc Coating ◽  
Pressure Steam ◽  
Adhesion Friction

We evaluated the adhesion, friction characteristics, durability against bodily acids, sterilization, cleaning, and anti-reflection performance of diamond-like carbon (DLC) coatings formed as a surface treatment of intracorporeal medical devices. The major coefficients of friction during intubation in a living body in all environments were lower with DLC coatings than with black chrome plating. DLC demonstrated an adhesion of approximately 24 N, which is eight times stronger than that of black chrome plating. DLC-coated samples also showed significant stability without being damaged during acid immersion and high-pressure steam sterilization, as suggested by the results of durability tests. In addition, the coatings remained unpeeled in a usage environment, and there was no change in the anti-reflection performance of the DLC coatings. In summary, DLC coatings are useful for improving intracorporeal device surfaces and extending the lives of medical devices.

SUBSTANTIATION OF OPTIMAL PARAMETERS AND DEVELOPMENT OF HIGH-TEMPERATURE STERILIZATION MODES FOR COMPOTE FROM PEARS IN HEATED AIR FLOW

2020 ◽  
Author(s):  
М.Э. Ахмедов ◽  
А.Ф. Демирова ◽  
Г.И. Касьянов ◽  
Ю.Ф. Росляков ◽  
М.М. Рахманова
Keyword(s):  
Mathematical Model ◽  
High Temperature ◽  
High Speed ◽  
Heat Transfer Fluid ◽  
Initial Product ◽  
Hot Air ◽  
Heated Air ◽  
Sterilization Process ◽  
Thermal Sterilization ◽  
Heat Carriers

Разработаны новые режимы стерилизации компота из груш в стеклотаре СКО 1-82-1000 с использованием высокотемпературных скоростных теплоносителей. Получена математическая модель расчета продолжительности процесса стерилизации в зависимости от параметров теплоносителя. Для получения математической модели использован метод математического планирования эксперимента. Предложен технологический прием ускоренной стерилизации компота из груш в стеклобанке объемом 1 дм3. Разработаны новые режимы тепловой обработки (стерилизации) компота из груш в стеклобанке 1-82-1000 при различных параметрах горячего воздуха и разных начальных температурах продукта, °С: 70, 80, 85 и 90. Наименьшая продолжительность процесса тепловой стерилизации достигнута при скорости теплоносителя 7,5 м/с при начальной температуре продукта 90°С. New modes of sterilization of compote from pears in glass containers of SKO 1-82-1000 using high-temperature high-speed heat carriers have been developed. A mathematical model for calculating the duration of the sterilization process depending on the parameters of the heat carrier is obtained. To obtain a mathematical model, we used the method of mathematical planning of the experiment. A technological method for accelerated sterilization of pear compote in a glass jar with a volume of 1 dm3 is proposed. The research made it possible to develop new modes of heat treatment (sterilization) of compote from pears in a glass jar 1-82-1000 at different parameters of hot air and different initial temperatures of the product, °C: 70, 80, 85 and 90. The shortest duration of the thermal sterilization process is achieved at the heat transfer fluid speed of 7,5 m/s at the initial product temperature of 90°C.

Estimation of the Time Delay Associated With Damping Controlled Fluidelastic Instability in a Normal Triangular Tube Array

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
John Mahon ◽  
Craig Meskell
Keyword(s):  
Time Delay ◽  
Cross Flow ◽  
Fluid Forces ◽  
Fluidelastic Instability ◽  
Order Of Magnitude ◽  
Sample Frequency ◽  
Pitch Ratio ◽  
Parameterized Model ◽  
Semi Empirical ◽  
Insight Into

Fluidelastic instability (FEI) produces large amplitude self-excited vibrations close to the natural frequency of the structure. For fluidelastic instability caused by the damping controlled mechanism, there is a time delay between tube motion and the resulting fluid forces but magnitude and physical cause of this is unclear. This study measures the time delay between tube motion and the resulting fluid forces in a normal triangular tube array with a pitch ratio of 1.32 subject to air cross-flow. The instrumented cylinder was forced to oscillate in the lift direction at three excitation frequencies for a range of flow velocities. Unsteady surface pressures were monitored with a sample frequency of 2 kHz at the mid plane of the instrumented cylinder. The instantaneous fluid forces were obtained by integrating the surface pressure data. A time delay between the tube motion and resulting fluid forces was obtained. The nondimensionalized time delay was of the same order of magnitude assumed in the semi-empirical quasi-steady model (i.e., τ2 = 0.29 d/U). Although, further work is required to provide a parameterized model of the time delay which can be embedded in a model of damping controlled fluidelastic forces, the data already provides some insight into the physical mechanism responsible.

scholarly journals Numerical Analysis of the Rudder–Propeller Interaction

2020 ◽  
Vol 8 (12) ◽  
pp. 990
Author(s):  
Diego Villa ◽  
Andrea Franceschi ◽  
Michele Viviani
Keyword(s):  
Flow Problem ◽  
Empirical Method ◽  
Design Stage ◽  
Mutual Position ◽  
Flow Solver ◽  
Additional Information ◽  
Computational Fluid Dynamics Cfd ◽  
Semi Empirical ◽  
Insight Into ◽  
Numerical Approaches

The proper evaluation of the Rudder–Propeller interactions is mandatory to correctly predict the manoeuvring capability of a modern ship, in particular considering the commonly adopted ship layout (rudder often works in the propeller slipstream). Modern Computational Fluid Dynamics (CFD) solvers can provide, not only the performance of the whole system but also an insight into the flow problem. In the present paper, an open-source viscous flow solver has been validated against available literature experimental measurements in different conditions. After an extensive analysis of the numerical influence of the mesh arrangement and the turbulent quantities on the rudder provided forces, the study focused its attention on the forces generated by the rudder varying the propeller loading conditions and the mutual position between the two devices. These analyses give a hint to describe and improve a commonly-used semi-empirical method based on the actuator disk theory. These analyses also demonstrate the ability of these numerical approaches to correctly predict the interaction behaviour in pre-stall conditions with quite reasonable computational requests (proper also for a design stage), giving additional information on the sectional forces distribution along the span-wise rudder direction, useful to further develop a new semi-empirical rudder model.

Immobilized Bacterial Spores for Use as Bioindicators in the Validation of Thermal Sterilization Processes

2002 ◽  
Vol 65 (7) ◽  
pp. 1134-1141 ◽  
Author(s):  
D. SERP ◽  
U. von STOCKAR ◽  
I. W. MARISON
Keyword(s):  
Thermal Resistance ◽  
Bacillus Stearothermophilus ◽  
Alginate Beads ◽  
Temperature Sensitive ◽  
Low Concentrations ◽  
Microwave System ◽  
C Value ◽  
Sterilization Process ◽  
Thermal Sterilization ◽  
Ph Range

Spores of Bacillus subtilis ATCC 6051 and Bacillus stearothermophilus NCTC 10003 were immobilized in monodisperse alginate beads (diameter, 550 μm ± 5%), and the capacity of the immobilized bioindicators to provide accurate and reliable F-values for sterilization processes was studied. The resistance of the beads to abrasion and heat was strong enough to ensure total retention of the bioindicators in the beads in a sterilization cycle. D- and z-values for free spores were identical to those for immobilized spores, which shows that immobilization does not modify the thermal resistance of the bioindicators. A D100°C value of 1.5 min was found for free and immobilized B. subtilis spores heated in demineralized water, skimmed milk, and milk containing 4% fat, suggesting that a lipid concentration as low as 4% does not alter the thermal resistance of B. subtilis spores. Providing that the pH range is kept between 3.4 to 10 and that sufficiently low concentrations of Ca2+ competitors or complexants are present in the medium, immobilized bioindicators may serve as an efficient, accurate, and reliable tool with which to validate the efficiency of any sterilization process. The environmental factors (pH, media composition) affecting the thermoresistance of native contaminants are intrinsically reflected in the F-value, allowing for a sharper adjustment of the sterilization process. Immobilized spores of B. stearothermophilus were successfully used to validate a resonance and interference microwave system that is believed to offer a convenient alternative for the sterilization of temperature-sensitive products and medical wastes.

scholarly journals Rim Sealing of Rotor-Stator Wheelspaces in the Presence of External Flow

1994 ◽  
Author(s):  
J. W. Chew ◽  
T. Green ◽  
A. B. Turner
Keyword(s):  
Model Experiment ◽  
Reasonable Agreement ◽  
Three Dimensional ◽  
External Flow ◽  
Rotating Disc ◽  
Gas Concentration ◽  
Computational Fluid Dynamics Cfd ◽  
Axial Clearance ◽  
Insight Into ◽  
Circumferential Pressure

Sealing of the cavity formed between a rotating disc and a stator with an asymmetric external flow is considered. In these circumstances circumferential pressure variations in the external flow and the pumping action of the disc may draw fluid into the cavity. Gas concentration measurements, showing this effect, have been obtained from a model experiment with a simple axial clearance seal. In the experiment, guide vanes, fitted upstream of the rim seal, generate an asymmetric external flow. The measurements are shown to be in reasonable agreement with three-dimensional computational fluid dynamics (CFD) calculations and are also compared with more elementary models. The CFD results give further insight into the effects of ingestion within the cavity.

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